sum a series - algebra

Find the sum of the series

Using the above result , find the value of .

My working

The question says use the above result and this is what i am confused with . How to use the result above to determine the sum of the following series . Is this the method of differences ? If yes , how do i apply ?

The question says use the above result and this is what i am confused with . How to use the result above to determine the sum of the following series . Is this the method of differences ? If yes , how do i apply ?

you know the formula for the sum of the first n squares. the first part is about the sum of the first even squares (that is, the squares of even integers), the second is asking for the sum of the first n odd squares. do you see what to do now? yes, finding a difference is involved